The brother of a Colombian Cabinet minister has been arrested in connection with a criminal probe involving politicians suspected of having ties with far-right paramilitary squads.

Senator Alvaro Araujo, the brother of Foreign Minister Maria Consuelo Araujo, was detained Thursday in a shopping center in the capital city of Bogota. Arrest warrants have also been issued for five other politicians.

Three other legislators suspected of collaborating with the far-right militias were arrested in November. The militias were formed in the 1980s by wealthy ranchers to battle leftist rebels. They evolved into powerful criminal gangs that engaged in drug trafficking, civilian massacres and other atrocities.

Some 31,000 paramilitaries have demobilized as part of a peace plan with the government aimed at ending Colombia's 43-year civil war.